1. Field of the Invention
The present invention relates to a pushbutton input device with a plurality of pushbuttons arranged for entering commands, characters, and other entries as well as transmitting radio signals in response to a depressing operation of the pushbuttons, a remote control equipped with the pushbutton input device, and a method of manufacturing a pushbutton unit for use in the pushbutton input device.
2. Description of the Related Art
Conventionally, there exists a pushbutton input device that has a plurality of pushbuttons arranged and that enters commands, characters, etc. and transmits radio signals in response to a depressing operation of the pushbuttons in remote controls for remotely controlling TVs, videos, air conditioners, etc. or cellular phones, electric calculators, etc.
Such a pushbutton input device has a rubber button 30 which is a pushbutton unit as shown in FIG. 8 equipped inside a case. Rubber button 30 has a construction with a plurality of pushbuttons 31 arranged in a form of matrix on one flexible sheet section 32 and formed integrally. In addition, on the back side of each pushbutton 31, conductive material is applied.
Rubber button 30 is mounted inside a case with openings that correspond to the arrangement of pushbuttons 31 and with pushbuttons 31 exposed from the openings. In addition, there is equipped inside the case a circuit board with electric contact pairs formed, each pair of which come in contact with the conductive material applied on the backside of pushbutton 31 when pushbutton 31 is depressed and achieve electrical conduction.
In a conventional pushbutton input device having such a construction, pressing pushbuttons 31 electrically connects electric contact pairs on a circuit board, so that the device detects the depression of pushbuttons 31 for input of commands, characters, etc. and for transmission of radio signals in response to the depression.
In the meantime, a rubber sheet is known which permits unit sheets to be manufactured using the same mold, even when the size of unit sheets or the number of key tops may differ (for example, see Japanese Patent Laid-open Publication No. HEI 4-366514).
However, because in rubber button 30 of the conventional pushbutton input device described above, sheet section 32 encompasses the excess area between arrangements of pushbuttons 31, rubber material was used wastefully. In addition, since one rubber button 30 was formed with one piece of sheet section 32, in forming a plurality of rubber buttons 30, marking printing must be provided on the surface of pushbutton 31 and electrically conductive material must be applied to the backside of pushbuttons 31 for every rubber button 30. Even if the contents described in Japanese Patent Laid-open Publication No. HEI 4-366514 are applied, the above mentioned problems are unable to be solved.